How to create a collage or mosaic of multiple images in Go?

To create a collage or mosaic of multiple images in Go, you can utilize the github.com/disintegration/imaging library. This library provides functionalities to perform image manipulation tasks, including resizing, cropping, and drawing.

Here's an example of how you can create a simple collage using the imaging library:

package main

import (
	"image"
	"image/draw"
	"image/jpeg"
	"log"
	"os"

	"github.com/disintegration/imaging"
)

func main() {
	// Load the images
	img1, err := imaging.Open("image1.jpg")
	if err != nil {
		log.Fatalf("failed to open image1.jpg: %v", err)
	}

	img2, err := imaging.Open("image2.jpg")
	if err != nil {
		log.Fatalf("failed to open image2.jpg: %v", err)
	}

	img3, err := imaging.Open("image3.jpg")
	if err != nil {
		log.Fatalf("failed to open image3.jpg: %v", err)
	}

	// Resize the images to the desired size
	size := image.Pt(200, 200)
	resized1 := imaging.Resize(img1, size.X, size.Y, imaging.Lanczos)
	resized2 := imaging.Resize(img2, size.X, size.Y, imaging.Lanczos)
	resized3 := imaging.Resize(img3, size.X, size.Y, imaging.Lanczos)

	// Create a new blank canvas for the collage with the desired size
	collage := imaging.New(size.X*3, size.Y)

	// Draw the resized images onto the collage
	offsetX := 0
	draw.Draw(collage, image.Rect(offsetX, 0, offsetX+size.X, size.Y), resized1, image.Point{}, draw.Src)

	offsetX += size.X
	draw.Draw(collage, image.Rect(offsetX, 0, offsetX+size.X, size.Y), resized2, image.Point{}, draw.Src)

	offsetX += size.X
	draw.Draw(collage, image.Rect(offsetX, 0, offsetX+size.X, size.Y), resized3, image.Point{}, draw.Src)

	// Save the resulting collage as a new image file
	resultFile, err := os.Create("collage.jpg")
	if err != nil {
		log.Fatalf("failed to create collage.jpg: %v", err)
	}
	defer resultFile.Close()

	jpeg.Encode(resultFile, collage, nil)
}

In this example, the imaging.Open function is used to load three input images, which are then resized to a desired size using imaging.Resize function. These resized images are then drawn onto a new blank canvas (collage) using the draw.Draw function. Finally, the resulting collage image is saved as a new file using jpeg.Encode.

Make sure to replace the file names with the actual file names or paths of the images you want to use in your collage.